Gould on the Cambrian Explosion
Here is what well-known Harvard paleontologist Stephen J. Gould had to say about the fossils of the Cambrian Explosion:
The Cambrian explosion is the key event in the history of multicellular animal life. The more we study the episode, the more we are impressed by its uniqueness and of its determining effect on the subsequent pattern of life's history. These basic anatomies that arose during the Cambrian explosion have dominated life ever since, with no major additions. The pattern of life's history has followed from the origins and successes of this great initiating episode. S. J. Gould, Of Tongue Worms, Velvet Worms, and Water Bears, Natural History 104 (1995), 15.
Kansas science standards now include reference to these fossils. And the Washington Post thinks that is unconstitutional.
I wish a major media outlet would do a program about these amazing fossils, and why many lobbyists are trying to keep information about them out of science classes. I wish a reporter would ask a leading politician whether she thinks Kansas was right or wrong to include these fossils in their science standards. Instead of intelligent design, let's have a national debate on the Cambrian fossils.
posted by Lawrence Selden @ 11:52 AM
15 comments
15 Comments:
That doesn't mean that some designer suddenly created a bunch of cambrian organisms. Stephen Jay Gould explains that evolution necessarily occurs not gradually and consistently, but in fits and spurts... Here's an excellent quote of the professor on the subject:
"The modern theory of evolution does not require gradual change. In fact, the operation of Darwinian processes should yield exactly what we see in the fossil record. It is gradualism that we must reject, not Darwinism. […] Eldredge and I believe that speciation is responsible for almost all evolutionary change. Moreover, the way in which it occurs virtually guarantees that sudden appearance and stasis shall dominate the fossil record. All major theories of speciation maintain that splitting takes place rapidly in very small populations. The theory of geographic, or allopatric, speciation is preferred by most evolutionists for most situations (allopatric means ‘in another place’). A new species can arise when a small segment of the ancestral population is isolated at the periphery of the ancestral range. Large, stable central populations exert a strong homogenizing influence. New and favorable mutations are diluted by the sheer bulk of the population through which they must spread. They may build slowly in frequency, but changing environments usually cancel their selective value long before they reach fixation. Thus, phyletic transformation in large populations should be very rare — as the fossil record proclaims. But small, peripherally isolated groups are cut off from their parental stock. They live as tiny populations in geographic corners of the ancestral range. Selective pressures are usually intense because peripheries mark the edge of ecological tolerance for ancestral forms. Favorable variations spread quickly. Small peripheral isolates are a laboratory of evolutionary change.
What should the fossil record include if most evolution occurs by speciation in peripheral isolates? Species should be static through their range because our fossils are the remains of large central populations. In any local area inhabited by ancestors, a descendant species should appear suddenly by migration from the peripheral region in which it evolved. In the peripheral region itself, we might find direct evidence of speciation, but such good fortune would be rare indeed because the event occurs so rapidly in such a small population. Thus, the fossil record is a faithful rendering of what evolutionary theory predicts, not a pitiful vestige of a once bountiful tale."
— "The Episodic Nature of Evolutionary Change," The Panda's Thumb: Reflections in Natural History, New York: W. W. Norton & Company, 1980, pp. 182-184.
Done and done. Gradualism is simply how IDers like to present evolutionists' claims, but that is a gross misrepresentation. More "obscurantism" from the theologues - have I made my point yet?
I agree with Stewie but i would like to add that the theory of evolution is an approximation to truth with which many scientific advances (esp. in medicine) have been made. Life is often more complex than one theory can capture. Evolution of course takes place within an environment and is influenced by many factors. Climate change, rotation and interstellar constellations are all theoretically plausible to influence the speed or direction of evolution. On the other hand, I do not see any evidence for "intelligent design". Quite on the contrary, I see intelligent design as an egocentric and perhaps even arrogant notion of mankind. Men are certainly nowhere near any kind of perfection as is evidenced by war, irrational behavior, and countless other things. So where did God then make the mistake???
It's obvious that Stewie doesn't keep track of developements; perhaps because they don't suit his point of view. That's a common human failing.
The argument that:"our fossils are the remains of large central populations." isn't strictly accruate; and in any case, other sources such as DNA have largely taken over the running from palaeontology.
He's obviously not aware, for example, of the existence of the 'ancestral mother' or "The Real Eve". Geneticists (working out of Oxford Uni.) established some years ago that a single woman, dating back 150,000 years,
is the common ancestor of "modern man".
They traced the journey (via mitochondrial DNA) of her descendants from East Africa to Indonesia and Australia, before they arrived in Europe 50,000 years ago.
They deliberately make the point that "Eve was not the only woman there, but her genetic makeup was the only one to survive."
The broader point is that finding flaws (real or imagined)in Darwin's work is about as stupid as denigrating the inventor of the wheel because he didn't build a Ferrari.
I fail to see where our great disagreement here is, Michael. The Real Eve hypothesis is seductive, but as you've presented it, is not the full story. It's completely obvious that "her genetic makeup was the only one to survive" given the very nature of mitochondrial DNA, as it is traced exclusively maternally. So, don't mistake her for our common genetic ancestor - she is merely the *most recent* common ancestor *of humans alive today* that we've discovered WRT matrilineal descent. Therefore, don't go labelling her as our lone mother. Your dad's mom (who also passed on her matrilineal mitochondrial DNA on to her daughters) is an example of an ancestor who is not matrilineal to you. She did, however, actually exist, and at roughly the same time as your mother's mom.
Additionally, "The Real Eve" did live with many other individuals, both men and women. When she was alive, she was not that period's "Mitochondrial Eve" as that distinction was held by a distant ancestor of hers, and the many humans who were that ancestor's contemporaries. Now, even if we had actually found our current "Real Eve" here, the fact remains that many other women lived with her, but they either did not leave descendents or did not leave descendents via the matrilineal line, who are still alive today. This is all not even exploring the fact that a sudden drop in population will condense the ancestral pool to a size as to render a new mitochondrial Eve for all her progeny.
So, the title of "The Real Eve" as we've dubbed it is entirely dependant on the present human population of Earth, and as people die and are born, the title can change hands. Once a matrilineal Eve is established (via the death of a matrilineal line), further births cannot change the title. Further deaths can, however, transfer the title to a more recent woman. You might want to read that last sentence again, because the older matrilineal Eve is still the common ancestor of all humans alive today on Earth with respect to matrilineal descent, but she is not the most recent.
AND... just to drive home the point that whomever we find at the time to be the matrilineal or "real" Eve most likely is not the actual one, scientists have also identified the Y-chromosome Adam, and he's been dated to be much more recent times than the matrilineal Eve. That sure must irritate the Bible thumpers, that our currently-identified Adam and Eve lived tens of thousands of years apart.
Long story short, the matrilineal Eve is a mathematical imperative, as that specimen will be the first ancestor to pass on mitochondrial DNA in the specific manner that we continue to inherit. Logically, that specimen had to exist, so her discovery wasn't huge news. The more important data, though, is WHEN she existed, as that actually tells us something about the ancient evolution of the human species.
So, yes Michael, I am aware of her. Her discovery doesn't really prove anything, and I still don't see where we disagree.
I listend to Gould speak, okay once, and he seemed to really give the absoulte miracle of how we all came to be. It seemed Gould did the same thing that Carl Sagan did... spend a lot of time denying any purpose of life or any type of design.
... A common Christian reaction when someone poses an idea that can work independant of a divine creator.
Stewie
"ID is not science. If it belongs anywhere (frankly I don’t think it does) ID’s place is in comparative religion or philosophy classes at the college level, not in high school bio classes."
A common naturalist reaction when someone poses an idea that can work independant of evolution.
The difference is, my reaction is prompted and supported by overwhelming observable evidence, and the other is substantiated only by untestable pretentions to the supernatural.
Overwhelming to who? It's unthinkable to say that it's unthinkable for a thinker to not think the same thoughts that the thinker thinks.
Now that's funny right there, I don't care who you are!
Stewie is misleading us if he/she wants us to believe that Gould's controversial views represent how evolutionists typically think.
The problem with Gould's theory is the problem that people have been pointing out all along in their attacks on him: it is just massively improbable that such major changes as Gould postulates for isolated populations would occur in very short time frames.
Dawkins and Dennett have views that do not accord with the evidence, while Gould has views that accord with the evidence, but are frankly unbelievable.
The only way out: Intelligent Design, baby!
The "pick your denomination" viewpoint you presuppose is endemic of a provincial belief in limited doctrine.
"Ooh... these two guys disagree on minor points of a huge field with another guy, and then even the two guys disagree on still smaller issues between themselves!!! Gotcha!!! Evlushun is for morans!LOL!!!111oneoneone"
Grow up.
You're arguing anacrhonistic points and recasting quotes out of context. Evolution indeed does not trend toward greater complexity, but toward functionality enabling a survival and/or reproductive advantage.
The fossil record is nowhere near complete. If it were, we would have no need for the fields of paleontology, paleobotany, or paleo-anything. We're finding new disnosaurs and other organisms all the time.
Mr. Gould and I are in agreement, and there's nothing that inherently contradicts the incompleteness of the fossil record in the Paul quote. He's saying that we should let the fossils do the talking, nothing wrong with that.
But you see creationism wherever you want to see it. If you knew the first thing about the precambrian and cambrian eras, you would be able to bring some knowledge and insight to these quotes. But you obviously don't, so you read them as cambrian era = creation of animals. Sigh.
First off, the cambrian explosion does not show all groups appearing together fully formed. Left out are plants, fungus, and microbes. As the cambrian era was the first appearance of hard body parts such as teeth and shells, there wasn't much around in the precambrian era to fossilize. The precambrian era was also a really long time ago, and few fossils survive from that era. They don't get better with age, you know. But it's all consistent with what we'd expect from an evolutionary tree: bacteria show up before multicellular organisms, and we've found fossils giving evidence of transitionals leading to arthropods and other life. On to the next post. Serving up the softballs here:
Why are morphological gaps plentiful, large, and sytematically placed?
For fossil records to exist, an event (most of the time, many events) need(s) to occur to bury and fossilize the organisms. Such events do not occur with predictable or consistent regularity (and not to predictable or consistent degrees), so not every organism gets fossilized, thus not every species gets represented equally in the fossil record.
Why are the gaps so large that they cannot be bridged by experimental demonstration?
I was not aware that you could discover a fossil in the earth by running a lab experiement.
Why does the record of life fail to show substantial patterns of lineage and phylogeny?
Lineage? Hah! You're simply ignoring discovery after discovery to claim that one. Remember Australopithecine("Lucy")? or Floresiensis? or Neanderthalensis? or the other sixteen (documented) precursors to homo sapiens sapiens?
Phylogeny is disputed only by the creationist crowd. Finite occurrences of evolution by strict phylogenesis does nothing to dispute the relevance of phylogeny, it's clear that phylogeny takes a back seat to speciation, though it does exert an influence.
Why do embryological similarities commonly exist between quite different organisms said to have been separated by 3-4 hundred million years?
You ask this after asserting no evidence of lineage whatsoever... Did you actually check these questions all together after you copied and pasted them?
No multicellular animal produces the enzyme necessary to digest cellulose. That fact helps make the system of life ecologically stable. Yet evolution cannot look ahead to the future, or plan for the stability of an ecological system by prohibiting designs that would be beneficial to individuals. Evolutionists say this was by chance. The necessary enzyme, cellulose, was not inherited by, converged on, or transposed into multicellular animals.
Developments such as these are commensurate with a diet that grew to rely more heavily on things that don't have plant coverings. Things like meat. We've even found that primates who eat a lot of cellulose (or at least, plants) have larger appendixes than those who rely on other food. That discovery is still undergoing study at this point.
The human appendix is closely related to (actually, closely related enough to appear to be a functionless appendage of) a completely developed organ in other animals, like rabbits and many other herbivores, where a large cecum and appendix store vegetable cellulose to digest it along with bacteria. You forgot to phrase that in the form of a question... Once again, nitpicking at evolution and not asking novel scientific questions.
And we have'nt even covered DNA........
Let me guess:
"There's no such thing as junk DNA"
"DNA cannot assemble itself because it is information"
"Working genetic sequences are too rare/complicated/whatever to evolve from one to another"
"Scientific claims of quantitative human-chimp DNA similarities have been changing lately"
... It's like a scheduled liturgy with the creationist crowd.
Just about everything you've "asked" over the last few days has been claimed by creationists for years, and can be debunked by a modicum of knowledge and logic, and has been over and over. Repeating the question doesn't make it into a new objection. That "reassortment" one was new to me though... very cute. Let's see if you come up with any original questions - you know, the kind that come out of your own head. Bonus points if they're scientific and not religious or philosophical.
Clever of you to try and differentiate the 'scientific' from the 'religious or philosophical'. The problem is that many 'scientists' like Ruse, Dawkins, or Gould, despite their protestations to the contrary, attempt to explain the existence of the religious and philosophical impulses within humans in 'scientific' terms. So I reject your artificial distinction between the scientific, and the religio/philosophic, and demand my bonus points anyway :-)
Here's the question: what is the evolutionary explanation for the existence of notions of morality among humans? Can you come up with anything categorically different than either of these: genetic influences leftover from when we were herd animals on the Serengeti (or whatev); or 'societal evolution' such that communities that pass on notions of morality tend to survive better than those that don't?
If these are the only ways to explain morality (and, according to the philosophical naturalist, they ought to be), then any notion of morality I have, including prohibitions against theft, etc, are simply programming of one sort or another. Now that I know that, if these notions of morality are in conflict with any other desire I have, why should I follow the moral notions?
I am not a paleontologist, a geologist, an ‘evolutionary zoologist’ (or whatever they call themselves), or even a Ph.D. biologist. I suspect few of those commenting on this issue are, either. I have a bachelor’s in biology and an M.D., but these do not qualify me to critique the research involved.
There are people with degrees in the relevant fields, however, who deeply question the theory of evolution, and even declare that it should not properly be considered a theory, as it lacks some of the crucial qualifications of one. Many also maintain that the scientific data corresponds nicely with the text of Scripture, and not with evolutionary theory.
Since there are those with Ph.D.’s in the relevant fields who disagree with standard evolutionary theory, and since it contradicts a plain face reading of Scripture, I see no reason to grant it any credence. This is particularly so when it is clear to me, from a cursory reading of the writings of evolutionists, that many of them start with philosophically naturalistic assumptions, which I know to be false from the outset. Also, it is clear that a logical outworking of evolutionary theory as it is commonly presented is the conclusion that morality is meaningless. Since I know that morality is meaningful, I am justified in rejecting evolutionary theory.
And, on a final note, most of the philosophical naturalists and theistic evolutionists that I know have none or few children. I have four, and I homeschool my kids. We're outbreeding you. Just think of it as evolution in action.
Stewie,
Thank you for taking the time to post thoughtful comments. I'm not used to that from people who favor evolution.
I still remember my high-school science classes. Back then, it was the gradualism demonstrated in the fossil record that proved evolution. I was actually mocked by the teacher (during class) for suggesting that the fossil did not demonstrate gradual improvements. He was still teaching the horse series. Of course, " embryonic recapituation" was still in the textbook. I wasn't even arguing against evolution (yet), just the facts.
So, now all the facts have changed over to what I was saying (okay, repeating) back in the 1980's, but the conclusions are still the same.
Is there ANY conceivable set of findings that would disprove evolution? (You may be my best hope for getting some kind of response to that question.) Evolution always seems to predict whatever the facts happen to be, but only with a 30 year delay.
Steve O
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